33.6% is the change from 500 to 668
Calculation steps:
[( 668 - 500 ) ÷ 500] x 100 = 33.6%
Formula
Percentage change = [(668 - 500) / 500] x 100
Subtract the new number by the original number
668 - 500 = 168
168 ÷ 500 = 0.336
0.336 x 100 = 33.6%
Example